Project Summary Title: Impacts of Urbanization on Vector Biology and Transmission of Dengue in China Dengue fever is an acute infectious disease caused by the dengue virus and transmitted by Aedes mosquitoes. Despite the intense control program in China, major dengue outbreaks have recently occurred in the urban area of Southern China. Control of mosquito populations is the only available strategy for prevention of dengue because there are no effective drugs for dengue. The use of chemical insecticides represents the most important element of vector control for dengue in China and worldwide. Our preliminary data indicates a rapid rise of pyrethroid resistance in the dengue vectors in urban areas of southern China. This competing renewal application will test the central hypothesis that frequent dengue outbreaks and intensive insecticide use in the urban environment lead to an emergence and spread of insecticide resistance in the dengue vector, which in turn increases vector population density and vectorial capacity for dengue. We proposed three interlinked specific aims: 1) to determine resistance level of dengue vector populations in urban and rural environments, 2) to develop new molecular tools for insecticide resistance surveillance through a better understanding of resistance mechanisms, and to conduct molecular surveillance of insecticide resistance in urban and rural environments, and 3) to determine the effect of insecticide resistance on mosquito survivorship, vector competence and vectorial capacity in urban and rural environments. We will focus on Aedes albopictus, a highly invasive species and the most important dengue vector in Southern China. The knowledge and tools from this project will help in guiding the selection of insecticides for dengue vector control, facilitate insecticide resistance surveillance and management, and enhance our understanding of dengue epidemiology in the urban environment where insecticide resistance is rapidly increasing.